arXiv subjects

G. Pancheri

Publications and source records attributed to G. Pancheri.

81 records · Page 5Linked to original sources

arXiv1998

Total Widths And Slopes From Complex Regge Trajectories

Maximally complex Regge trajectories are introduced for which both Re $α(s)$ and Im $α(s)$ grow as $s^{1-ε}$ ($ε$ small and positive). Our expression reduces to the standard real linear form as the imaginary part (proportional to $ε$) goes to zero. A scaling formula for the total widths emerges: $Γ_{TOT}/M\to$ constant for large M, in very good agreement with data for mesons and baryons. The unitarity corrections also enhance the space-like slopes from their time-like values, thereby resolving an old problem with the $ρ$ trajectory in $πN$ charge exchange. Finally, the unitarily enhanced intercept, $α_ρ\approx 0.525$, \nolinebreak is in good accord with the Donnachie-Landshoff total cross section analysis.

hep-ph↗

arXiv1997

On the LEP Measurements of the Rising Photon-Photon Total Cross Section

Using vector meson dominance we calculate the $γγ$ total cross section from data on $pp$, $p\bar p$ and $γp$ total cross sections. Our result agrees with recent high energy measurements performed by the L3 experiment at the LEP collider, not with the conflicting preliminary data obtained by OPAL.

hep-ph↗

arXiv1997

Regge Trajectories For All Flavors

Based on available data for mesonic resonances of light, medium and heavy flavors, we have performed a global analysis to construct the corresponding linear Regge trajectories. These have been supplemented by results from various phenomenological models presented in the literature. A satisfactory formula is found for the dependence of the intercept and the slope on quark masses. We find reasonable agreement with data on production of charmed hadrons through exchange of our charmed trajectories in the space-like region. When applied to mesons containing the top quark, our results suggest the impossibility of their formation as evidenced by other independent analyses.

hep-ph↗

arXiv1997

Photon-Photon total inelastic cross-section

We discuss predictions for the total inelastic gamma-gamma cross-section and their model dependence on the input parameters. We compare results from a simple extension of the Regge Pomeron exchange model as well as predictions from the eikonalized mini-jet model with recent LEP data.

hep-ph↗

arXiv1996

Bloch-Nordsieck Summation and Partonic Distributions in Impact Parameter Space

A model for the parton distributions of hadrons in impact parameter space has been constructed using soft gluon summation. This model incorporates the salient features of distributions obtained from the intrinsic transverse momentum behaviour of hadrons. Under the assumption that the intrinsic behaviour is dominated by soft gluon emission stimulated by the scattering process, the b-spectrum becomes softer and softer as the scattering energy increases. In minijet models for the inclusive cross-sections, this will counter the increase from $σ_{jet}$ .

hep-ph↗

arXiv1996

Eikonalized mini-jet cross-sections in $γγ$ collisions

In this note we assess the validity and uncertainties in the predictions of the eikonalised mini-jet model for $σ^{inel}_{γγ}$. We are able to find a choice of parameters where the predictions are compatible with the current data. Even for this restricted range of parameters the predictions at the high c.m. energies, which can be reached at the TeV energy $e^+e^-$ colliders, differ by about $\pm 25\%$. LEP 2 data can help pinpoint these parameters and hence reduce the uncertainties in the predictions.

hep-ph↗

arXiv1996

Mini-jet Total Cross-sections and Overlap Functions through Bloch-Nordsieck Summation

Predictions for total inelastic cross-sections for photon induced processes are discussed in the context of the QCD-inspired minijet model. Large theoretical uncertainties exist, some of them related to the parton distributions of hadrons in impact parameter space. A model for such distribution is presented, based on soft gluon summation. This model incorporates (the salient features of distributions obtained from) the intrinsic transverse momentum behaviour of hadrons. Under the assumption that the intrinsic behaviour is dominated by soft gluon emission stimulated by the scattering process, the b-spectrum becomes softer and softer as the scattering energy increases. In minijet models for the inclusive cross-sections, this will counter the increase from $σ_{jet}$ .

hep-ph↗

arXiv1996

Gamma-Gamma Physics at LEP2

This report is an overview of the gamma-gamma physics capabilities of LEP2, and covers the following topics: structure functions, equivalent photon approximation, tagging conditions etc, soft and semihard physics, large-$p_t$ processes, heavy-quark physics, and exclusive channels.

hep-ph↗

arXiv1994

Effective Chiral Lagrangians with an SU(3)-Broken Vector-Meson Sector

The accuracy of effective chiral lagrangians including vector-mesons as (hidden symmetry) gauge fields is shown to be improved by taking into account SU(3)-breaking in the vector-meson sector. The masses, $M_V$, and couplings to the photon field and pseudoscalar pairs, $f_{Vγ}$ and $g_{VPP}$, are all consistently described in terms of two parameters, which also fit the values for the pseudoscalar decay-constants, $f_P$, and charge radii, $ $. The description of the latter is further improved when working in the context of chiral perturbation theory.

hep-ph↗